Human caliciviruses are among the most important causes of gastroenteritis. Despite the increasing awareness of these agents as a major cause of diarrheal illness, assays for the diagnosis of human calicivirus infection are not available to most clinical laboratories. There are also no effective antivirals available that can be used therapeutically or prophylactically for this infection. This project will focus on high throughput approaches to develop rapid diagnostic assays for the detection of human caliciviruses and high throughput assays to identify potentially effective antiviral agents. We hypothesize that the reagents and strategies developed in the previous project period to target shared epitopes can be optimized and used to develop broadly reactive diagnostic assays for these antigenically diverse viruses. In Specific Aim 1, we will further optimize broadly-reactive reagents that can be used to make diagnostic assays for human caliciviruses. Studies in this aim will optimize single chain (scFv) antibodies with a range of binding specificities and monoclonal antibodies that recognize conserved epitopes, both of which were developed and characterized in the previous funding period. In Specific Aim 2, we will develop broadly-reactive diagnostic assays for human caliciviruses. Rapid formats that will be useable in the field to detect human caliciviruses will be identified. High affinity, cross-reactive single chain and monoclonal antibodies characterized in specific aim 1 will be used in assays that require minimal sample preparation and yield a result in less than 30 minutes. Formats to be evaluated are those that have been used successfully for the detection of other human viruses and include solid-phase immunoassays, and latex agglutination assays. In Speciflc Aim 3, we propose to develop high throughput assays to screen agents for antiviral activity against human noroviruses. A high throughput screen for inhibitors ofthe viral protease will be used to identify inhibitor candidates from small molecule libraries. The results obtained from project 1 studies will lead to the availability of new assays for the diagnosis of these important enteric pathogens and the identification of antiviral agents with the potential to diminish the disease burden caused these agents.